For reasons that are not yet entirely clear, a California House of Assembly committee has killed a proposed bill seeking to legalise sports betting in the Golden State.

SB1390 appeared to ensure that California would be joining a growing number of US states restive at being excluded from the four-state roster of those permitted under the federal PASPA to offer sports betting.

It enjoyed wide support in the state Senate, where it passed on a 32 to 2 vote two months ago, and was progressed by the Assembly's Governmental Organization Committee a month later, seemingly well on the way to a floor vote and passage to the governor's desk.

However, earlier this week the measure appeared to have run afoul of the Assembly Appropriations Committee, which put it on the back burner for reasons that are not yet clear.

With the legislative session winding up at the end of August it has effectively been scuppered.

The action is surprising, given the bill's strong political support, and a Field Poll just two months ago which saw 58 percent of Californians supporting legalised state sports betting, with 35 percent against.